This invention relates to a one-piece, lightweight protective faceshield, particularly one having a viewing zone of maximum optical clarity, and a method of making such a faceshield.
Various types of faceshields are known in the art, many of which are designed to protect the wearer against flying projectiles. Such faceshields are generally comprised of multi-components, such as a clear viewing/shield portion affixed to a helmet or visor unit and are generally fabricated of relatively thick, impact-resistant plastic. There are generally known two preferred methods for fabricating a faceshield with acceptable optical clarity.
In one method, the faceshield may be injection molded in a mold that has a highly polished surface. Such processes generally require that the molded part have a thickness in excess of 0.040 inch (1.02 mm) to achieve reasonable polymer flow into the mold. Other than the thickness of the part, which is acceptable for most applications, this method produces very high quality precision parts of any desired configuration.
In a second method, a blank may be taken from an optically polished flat polymer sheet (the sheet is polished usually by pressing between two platens) and formed in a curved piece (i.e. cylindrical, not spherical) by heating the blank beyond its glass transition temperature and applying force in the direction of the desired curve. This method generally retains the optics of the original polished sheet, but is only suitable for simple curved pieces and cannot be utilized where the desired piece has a complex configuration.
It is now recognized that there is a need in the medical profession (the term "medical" as used herein is intended to encompass the medical, dental and related professions) for a lightweight, preferably disposable, faceshield to protect the medical professional from splattered body fluids so as to avoid the possibility of contamination therefrom. While certainly many of the heretofore known goggles and faceshields might serve this purpose, such products tend to be bulkier and heavier than is desired by the medical professional and are far too costly to be considered disposable.